How to create an .IMG image of a disc (sd card) without including free space?

Pretty good and simple way to deal with this is simply pipe it via gzip, something like this:

# dd if=/dev/sdb | gzip > backup.img.gz

This way your image will be compressed and most likely unused space will be squeezed to almost nothing.

You would use this to restore such image back:

# cat backup.img.gz | gunzip | dd of=/dev/sdb

One note: if you had a lot of files which were recently deleted, image size may be still large (deleting file does not necessarily zeroes underlying sectors). You can wipe free space by creating and immediately deleting large file containing zeros:

# cd /media/flashdrive# dd if=/dev/zero of=bigfile bs=1M     # let it run and quit by disk full error# rm bigfile

The best thing to do is

1. Copy all the files from all the partitions preserving meta data

   mkdir -p myimage/partition1

   mkdir myimage/partition2

   sudo cp -rf --preserve=all /media/mount_point_partition1/* myimage/partition1/

   sudo cp -rf --preserve=all /media/mount_point_partition2/* myimage/partition2/

2. Extract the MBR

   sudo dd if=/dev/sdX of=myimage/mbr.img bs=446 count=1

   replace /dev/sdX with the corresponding device.

3. Partition the destination disk into partitions with sizes greater than copied data and should be of the same format and same flags using gparted. Google how to partition a disk.

4. Mount the freshly formatted and partitioned disk. On most computers, you just need to connect the disk and you can find the mounted partitions in /media folder.

5. Copy the previously copied data to destination partitions using following commands

   sudo cp -rf --preserve=all myimage/partition1/* /media/mount_point_partition1/

   sudo cp -rf --preserve=all myimage/partition2/* /media/mount_point_partition2/

6. Copy back the MBR

   sudo dd if=myimage/mbr.img of=/dev/sdX bs=446 count=1

Now njoy Ur new disk!

Using the bs and count parameters of dd, you can limit the size of the image, as seen in step 2 of answer 1665017.

You may already know what size image you want to create. If not, you can get a good idea from df:

df -H --total /

Substitute / with a space-separated list of all the mount points relating to the disk partitions.

A more accurate way might be to use fdisk or your preferred partition editor and get busy with a calculator.

$ fdisk -l /dev/mmcblk0Disk /dev/mmcblk0: 7.4 GiB, 7948206080 bytes, 15523840 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisklabel type: dosDisk identifier: 0x00057540Device         Boot  Start     End Sectors  Size Id Type/dev/mmcblk0p1        2048  186367  184320   90M  c W95 FAT32 (LBA)/dev/mmcblk0p2      186368 3667967 3481600  1.7G  5 Extended/dev/mmcblk0p5      188416 3667967 3479552  1.7G 83 Linux

Total used space in bytes = end sector of last partition X sector size (here that's 3667967 x 512).

Total used space in GB = total used space in bytes / 1024³ (here that's 1.749023 GB).

If you decide, for example, that your image should be exactly 2 GB, the following command will do that:

dd if=/dev/mmcblk0 of=/path/to/pi_updated.img bs=1M count=2048

The resulting image will also include the random noise beyond the greatest extent of the last partition.

Don't forget to sudo the above commands if your account doesn't already have sufficient privileges.

For my purposes, I don't need an image that is perfectly trimmed down to the last bit of data so when the real size is 1.75 GB then a 2 GB image is near enough for me. This cuts out the other 6 GB (or 30 GB or whatever the device has spare) of unused space that would otherwise be in the image.

I have seen advice in many places that dd should not be performed on a mounted partition and I followed that because it seems intuitively correct; it does seem rather like trying to sketch yourself making a sketch in a mirror with the sketch you're making also visible in the sketch. It's a bit sketchy.